More particularly, the present invention relates to an adjustable shock absorber, that is to say a shock absorber whose damping characteristic can be influenced while driving. From the prior art, designs are known in which the pressure on the main valve is influenced by sending an auxiliary flow to the piston. The known designs have the drawback that they need a particularly high adjustment speed which requires complicated electronics. In addition, sensors have to be fitted both to the wheel and to the body of the vehicle. Systems of this type which require large numbers of sensors are highly vulnerable and demand a great deal of expertise during fitting and/or maintenance.